Premenstrual mood changes and gating of the auditory evoked potential

To assess the effect of the menstrual cycle on a measure of brain physiology known to be affected in psychiatric illness, auditory-evoked electroencephalographic potentials were recorded from 12 women on the day prior to menstruation and nine days after the initiation of their cycle. Eight were normal college students, and four were patients in a premenstrual syndrome clinic. The women showed significant changes in self-ratings of mood between the two recordings. The P50 wave of the auditory-evoked response was evaluated in a conditioning-testing paradigm, in which stimuli were presented in pairs, allowing assessment of putative excitatory and inhibitory processes involved in the gating of central nervous system sensory responsiveness to auditory stimuli. The auditory-evoked potentials were unchanged between the two recording periods. There was also no difference between the women and age-matched male controls. The data suggest that these central nervous system functions are not responsive to hormonal fluxes in menstruation. Since inhibitory gating of the P50 wave is lost in the manic phase of manic-depressive illness, the data also suggest that premenstrual mood changes in normal women do not share electrophysiological properties of mania.